(a) Field of the invention:
The present invention pertains to an apparatus for automatically producing rhythmically aligned tones by reading out stored waveshape data of a train of tones, and more particularly it relates to an apparatus for producing rhythmically aligned tones with live sound properties from stored waveshape data of a train of tones at various tempos but retaining the pitches of the respective tones.
(b) Description of the prior art:
Recently, in apparatuses designed for automatically producing tones such as automatic rhythm apparatuses and automatic accompaniment apparatuses, there has been adopted, for the purpose of improving the produced tone quality, a method of reproducing tones by preliminarily storing the entire waveshape of a single tone for each individual musical instrument by means of PCM (Pulse Code Modulation) recording, and by reading out the stored waveshape data in accordance with, for example, rhythm timing pulses (see, for example, U.S. Pat. No. 4,305,319). Also, there has been known the technique of storing, in a memory, the entire waveshape of a tone from the rise until the extinction thereof for each discrete musical instrument, and of reproducing the tones of the musical instruments by reading the stored waveshape data out of the memory in accordance with sounding commands (see, for example, Japanese Patent Preliminary Publication No. Sho 52-121313). In case such technique as these is applied to an automatic accompaniment apparatus of such as automatic chord, automatic arpeggio and automatic bass, it is possible to make the individual accompaniment tones which are produced in accordance with the accompaniment patterns resemble the tones of natural musical instruments. These methods have the drawback such that, because the occasionally (from-time-to-time) reproduced tones of a same musical instrument are all generated by reading-out the same single waveshape data for the entire tone, the tone quality of these produced tones as a same instrument are always uniform, and that therefore, it is impossible to reproduce subtle difference in tone quality with respect to the progression of the rhythm and/or in the relationship with other participating musical instruments, and that, thus, good performance with live sound properties can hardly be obtained.
Also, there has been proposed an automatic rhythm apparatus arranged so that those tones of respective rhythm-producing instruments which .have been produced successively to constitute each kind of are recorded on a magnetic tape, and that the recorded tones of these rhythm-producing instruments are repetitively reproduced (for example, see Japanese Patent Preliminary Publication No. Sho 49-59622). This apparatus, while there is obtained a pretty good live performance effect, is entailed by the drawback that alteration of tempo brings about a change in the pitches of the reproduced tones.
There has been known the technique that, when reproducing voice signals recorded on a magnetic tape, several cycles of the waveshape of a tone are blanked out periodically, and the respective sample values of the remaining waveshape are delayed for a desired length of time to enable alteration of the tempo while unchanging the pitch of the tone (see, for example, U.S. Pat. No. 3,786,195). When this latter-mentioned technique is adopted in the above-stated automatic rhythm apparatus using a magnetic tape, it becomes possible to alter the tempo without changing the pitch. However, because the portion at which the waveshape is blanked out is determined at a constant cycle irrespective of the tone producing timing, there could occur that the very rise (build-up) portion of the waveshape which is most critical for the tone quality is cancelled out, brings the inconvenience that the tone quality is extremely degraded.
Also, the problems which require solution when materializing a digital recording type automatic accompaniment apparatus of this kind lie, in the first place, in that the tempo can be altered without being entailed by pitch-changing or degradation of tone quality, and in the second place in minimizing the capacity of the waveshape data memory.